The survey showed the prevalence of both diagnosed and undiagnosed diabetes rose with BMI, from three per cent of normal weight adults, to 15 per cent of obese adults.

It is already known that type 1 diabetes is not linked to obesity so the figures show the risk of developing type 2 diabetes for obese people is five times higher than those of a normal weight.

The same pattern was also shown when people were measured around their waist.

Prevalence of diabetes among adults with ‘desirable’ – measured as less than 80cm for women and less than 94cm for men – and very high waist circumference was 2 per cent and 11 per cent respectively.

Dan Howarth, head of care for Diabetes UK said: “The results of this survey clearly show us that being obese carries with it an increased risk of developing type 2 diabetes.

“Although it was not measured in the survey we know that being overweight also puts you at a higher risk of developing this condition.

“We need people to recognise that being overweight or obese can have serious consequences for your health. Type 2 diabetes can lead to serious complications and we want people to ask for help to make the necessary changes to their lifestyle. People need to be encouraged and supported to eat more healthily and take more exercise.”